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The Navarro Frenk & White (NFW) model describes the (spherically symmetric) haloes of dark matter that form in cosmological simulations. It says that the density of dark matter follows the distribution +- p(r) = p(-) *-8 , where r is the distance from the center of the halo, and a is an arbitrary length. Show (using Poisson’s formula) that the potential consistent with this density distribution is \Phi(r)=-\sigma^2(\frac{r}{a})^{-1}ln(1+\frac{r}{a}) , where \sigma^2=4\pi G\rho_{0}a^2 .

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